1. Field of the Invention
The present invention relates generally to bearing assemblies and, more particularly, to a dual bearing assembly with means for automatically compensating for bearing wear and having an improved seal.
2. Description of the Prior Art
One previously known advertising display such as disclosed in U.S. Pat. No. 3,387,394 comprises a plurality of triangular louvers which are rotatably mounted in a frame and rotatably driven in unison with each other. Thus, different advertising messages are displayed as the louvers are rotatably driven to different rotational positions. These displays are driven by electric motors and a bearing assembly is typically interposed between the electric motor and each louver. The opposite end of each louver is connected by a shaft to the frame.
A primary disadvantage of these previously known display assemblies is that the components of the display assembly, and particularly the bearing assembly, are subjected to excessive wear due to their prolonged and continuous operation and as such, have previously required frequent maintenance and part replacement. Furthermore, when the bearing assemblies for these previously known display assemblies begin to wear, shaft wobble results which not only hastens the deterioration of the bearing assembly but also imposes undesirable loads and stresses on the electric motor. These loads not only damage the electric motor but may also necessitate its replacement.
A still further disadvantage of these previously known displays is that the shaft which connects the end of the louver opposite from the bearing assembly is typically fastened to the frame by a nut. After prolonged use, the nut frequently becomes loose which causes the display to malfunction.
A still further disadvantage of these previously known displays is that moisture, dirt and other contaminants enter into the bearing assembly. These contaminants cause bearing deterioration and, ultimately, malfunction of the display.